1. Field of the Invention
The present invention relates to the field of electrical machines, and in particular to a rotor.
A rotor such as this is known, for example, from the document DE-A1-28 52 980.
2. Brief Description of the Related Art
In the case of rotors such as those which are known from the initially cited DE-A1-28 52 980, EP-A1-0 334 020 or U.S. Pat. No. 4,143,457, a laminated rim which is formed from individual layers of rim laminates is connected by wedging to a rotor spider which is mounted such that it can rotate about a central axis. Depending on the way in which the rotor spider is produced, the laminated rim wedge system generally comprises a wedge support, a wedge and one or more mating wedges (see, for example, EP-A1-0 334 020 or U.S. Pat. No. 4,143,457). The rotor spider is a rigid structure in the area of the connection for the laminated rim, comprising two or more disks, the radial ribs (which may also be arranged tilted or obliquely when seen from the radial direction) and the wedge supports (see, for example, FIG. 2 in DE-A1-28 52 980). The ribs are welded to the disks and to the wedge supports and therefore cannot function as oblique elements in the area of the connection to the laminated rib, even if they are arranged obliquely. The wedge is rigidly connected to the laminated rim by a friction lock by means of the mating wedge (or the mating wedges).
The rim laminates have rectangular cutouts in order that the wedge and mating wedge or wedges can be accommodated. Two or more cutouts may be provided in the rim laminate. One or more wedges may also engage per laminate. The wedge and wedge support can move relative to one another. This is important because, if there were no capability for relative movement, the mechanical load on the rotor spider and on the rotor rim would be too high during operation (centrifugal force, different temperature distribution in the laminated rim and rotor spider).
The known laminated rim wedge system has the disadvantage on the one hand of the relatively major design and manufacturing complexity resulting from the wedge supports, the wedges and the mating wedges. On the other hand, the sliding movements between the wedge and the wedge supports can be controlled only with difficulty in practice. Finally, the laminated rim is quite often shrunk onto the rotor spider (see, for example, U.S. Pat. No. 4,143,457). However, the shrinking process results in high mechanical stresses being induced in the rotor spider when the rotor is at rest, which makes it necessary to design the rotor spider to be stiffer and more expensive.